CD19 and leukemia: Consistent with operating multiple mechanisms of cytotoxicity, CD19 CAR γδ T cells were found to exert not only CAR-directed activity against CD19+ leukemia cells but also CAR-independent activity against CD19- leukemia cells or cells which have lost expression of CD19 antigen (100), highlighting the advantage of using γδ T vis-à-vis αβ T cells.